Firefox is a redheaded stepchild for whichever terrible corporation owns Lastpass today. This extension is a broken mess on Firefox and is behind the Chrome extension by a mile (which is not great either). My job forced us on to Lastpass way before any greedy corporation bought it and it has gone straight downhill since. The worst part is how dumpster fire terrible their customer service is since the first buyout and every buyout since has made it worse.

Then there are issues of privacy and trust, you've got to be crazy to trust this closed source, proven to be greedy and customer-adversarial corporation with your most precious data. Thankfully I no longer am required to use Lastpass for work!

My advice is to delete your Lastpass account and move to Bitwarden (incredibly easy and fully step-by-step documented) or offline to Keepass.